The invention is directed to improving the heat exchange occurring in the heat treatment chamber of a furnace which is provided with radiant heaters or elements such as electrical resistances, radiant tubes, radiant burners, or the like. It has been found that certain types of multi-part loads such as, for example, racks of metal parts or ceramic pieces, are not properly heated in such furnaces.
The heat treatment of such loads has been improved by the use of fans which are provided to recirculate hot gas, exhausted from the chamber of the furnace, back to the chamber for impingement against the load. However, fans become inoperable above certain temperatures, thereby drastically limiting the temperature of the gas that can be recirculated to the chamber. The present invention is designed to improve the heat exchanges in radiant heater-type furnaces without resorting to the use of fans or other like devices which impose severe limitations upon the process.
Briefly stated, the invention concerns a process and device for improving the heat exchange in the heat treatment chamber of a radiant heater-type furnace, and is characterized by at least one nozzle which is designed to direct jets or streams of gas, under pressure, into the heat treatment chamber of the furnace in contact with a load positioned within the chamber. In the preferred embodiment, a plurality of nozzles are positioned such that the streams of gas, directed into the chamber, compliment and reinforce each other to produce an unusual swirling of gas within the furnace in the area of the load. The furnace is maintained, in balance, by exhausting from the chamber a volume of gas equal to that being blow into the chamber through the nozzles.
In another aspect of the invention, the exhaust gas is used to heat the incoming gas being circulated into the chamber through the nozzles.